Maxillary protraction device with chin-cup

ABSTRACT

A maxillary protraction device ( 12 ) characterized with a chin-cup ( 1 ); one or more front hook-levers ( 2 ) on the front section of said chin-cup ( 1 ) to exert a force horizontally and forwards to the maxilla; at least two lateral linear hooks ( 5 ) located at the sides of the chin-cup ( 1 ) to exert an upwards force to the mandible, front recess ( 6 ) to be used for engaging the hooks ( 2  and  5 ) to the chin-cup ( 1 ) to which the front hook is engaged in a length-adjustable manner, in the same number as that of hooks; and fixing members ( 9 ) in the same number as that of hooks.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage application of InternationalApplication No. PCT/TR02/00059 filed Sep. 27, 2002, claiming a prioritydate of Oct. 1, 2001, and published in the English language.

BACKGROUND OF THE INVENTION

The present invention relates to a Modified Maxillary Protraction Device(MMPD) designed for the treatment of growing skeletal and dentalopen-bite cases accompanied by maxillary development deficiency.

Since a long time, the treatment of skeletal Class III malocclusionsonly by using orthodontical methods has been accepted to be difficultand subject to obstinancy. Before the 1970's, Class III problems weredefined mainly as mandibular prognatisms, and maxilla has not been verymuch emphasized in the literature. Later studies have shown that a realisolated mandibular prognatism constitutes only 20–25% of Class IIIcases.

According to Sinclair and Proffit (Sinclair, P. M.; Proffit, W. R.:Class III Problems: Mandibular Excess/Maxillary Deficiency, inSurgical-Orthodontic Treatment. (ed.) Proffit, W. R.; White, R. P. St.Louis: Mosby, 1991, CH. 14, p: 428–482.) among the Class III anomalies,20–25% of the Class III population exhibited only maxillary deficiency,whereas 50–60% exhibited maxillary deficiency, together with mandibularprognatism. This rate increases up to 32–43% in the Japanese societywherein the incidence of Class III anomalies is quite high (Takada, K.;Petdachai, S.; Sakuda, M.; Changes in Dentofacial Morphology in SkeletalClass III Children Treated by a Modified Maxillary Protraction Headgearand a Chincup: A Longitudinal Cephalometric Appraisal, Eur. J. Orthod.15:211–221,1993.).

Excessive vertical development of the mandible, as well as its excessiveforwards development, is quite common in Class III abnormality groupsand constitutes a combination that can be seen in 6% of the patients.

The treatment plan for a skeletal Class III open-bite patient, duringhis/her growth period, should be aimed at both saggital and verticalanomalies, and excessive vertical growth of the mandible must beprevented while the forwards-downwards growth of the maxilla isencouraged.

In the devices used in the state of the art, the forwards development ofthe maxilla is provided and the forwards development of the mandible isinhibited. However, with the usage of maxillary protraction appliances,as the downwards growth of the mandible is not prevented, the length ofthe face increases. This situation may lead to the ‘long-face syndrome’wherein chin-face (craniofacial) surgical operations may be required inskeletodental open-bite cases. For such a surgical intervention, thepatient has to wait until he/she is 18 years old or a multi-phaseorthodontic treatment that may last for many years with separateapplications for the maxilla and mandible, has to be employed. Duringthe multiphase orthodontical treatment, first a reverse head gear isimplemented in order to increase the forwards maxillar development,however, the vertical open-bite status cannot be controlled by thisimplementation. Therefore the open-bite treatment is postponed to alater phase and requires the use of a separate apparatus.

Some orthodontists deem it convenient to wait until the completion ofthe growth of the Class III open-bite patients, without anyinterventions and upon the completion of their growth, to employsurgical methods to correct such anomalies. In the state of the art, inEU Patent No. 445492, the mandible is connected to magnets fastened bymeans of correcting levers to a control box. However here, only avertical force is exerted on the chin.

In Spanish Patent Application No. 97/43975, a similar device isdisclosed, whereby only a force in the vertical direction is applied onthe chin by using correcting elements. Furthermore, the correctingelements have no length adjustment and movement possibilities.

In both of these prior art devices, conformity to all types of patientfaces cannot be provided.

SUMMARY OF THE INVENTION

One object of the present invention is to prevent excessive verticalgrowth of the mandible and to provide an enhanced and rapid forwardgrowth of the maxilla, without causing facial elongation in the growingindividuals with Class III open-bite anomalies.

Another object of the present invention is to provide a simultaneousexertion of a horizontal-forwards force and a vertical-upwards force.

One other object of the present invention is to be able to terminate theexertion of the horizontal-forward force by removing the hooks when asufficient relationship in forwards-backwards direction, between themandible and the maxilla, is established.

Yet another object of the present invention is to be able to adjust thedevice in line with the facial structure of the individual.

Another object of the present invention is to realize the treatment in ashort time, without subjecting a growing individual with many tiringprocedures.

BRIEF DESCRIPTION OF THE DRAWINGS

The maxillary protraction device realized in order to attain the objectsof the present invention has been illustrated in the drawings wherein:

FIG. 1 is an exploded perspective view of a maxillary protraction deviceaccording to the present invention;

FIG. 2 is a profile view of the maxillary protraction device; and

FIG. 3 is an exploded perspective view of the maxillary protractiondevice.

DETAILED DESCRIPTION OF THE INVENTION

The maxillary protraction device (12) comprises a chin-cup (1); one ormore front hooks or hook members (2) on the front section of thechin-cup (1) to exert a force horizontally and forwards to the chin; atleast two lateral linear hooks or side hook members (5) located at theopposite sides of the chin-cup (1) to exert an upwards force to the chinorthogonally; a stationary or movable anchor act unit (13) placed on theupper palate; a head-piece (11) to be placed on the head; front openings(6) and lateral openings (7) for engaging the hooks (2 and 5) to thechin-cup (1), in the same number as that of the hooks; and fixing orlocking members such as screws (9) in the same number as that of thehooks.

The head-piece (11) can be made in various shapes provided that ittightly fits onto the head. At the ear level, the head-piece is providedwith flexible fastening members (8) to be connected to the lateral hooks(5) in order to exert an upwards force to the mandible.

The chin-cup (1) has a structure in conformity with the patients' chinstructure. The openings (6 and 7) are adapted to slidably receive thehooks (2 and 5) and are provided with a fixing member hole such as ascrew hole (10) in order to releasably fix the inserted hooks (2,5) inthe openings (6,7).

Each front hook (2) consists of a linear-section (3) and acurved-section (4). The linear section (3) is slidably adjusted to thedesired up-down position in the front opening (6) and is fixed by meansof the fixing or locking member (9).

Each lateral hook (5) with a lateral-linear form is slidably adjusted tothe desired front-rear position in the side or lateral opening (7) andis fixed by means of the fixing or locking member (9).

The front and lateral hooks (2 and 5) are preferably made of metal. Thefront openings (6) and the lateral openings (7) are formed in front andside fixtures F1 and F2 in the form of protrusions on the chin-cup (1).The front opening (6) has a length at least equal to the linear section(3) of the front hook (2) whereas the lateral opening (7) is at least aslong as the lateral-linear hook (5). The front openings (6) extendcompletely through the front fixtures F1 in a generally up-downdirection during use of the device (see FIGS. 2 and 3), and the lateralopenings (7) extend completely through the side fixtures F2 in agenerally front-rear direction during use of the device (12). The hooks(2 and 5) enter the openings from one end and project from the otherend.

The chin-cup (1) is connected to the head-piece (11) by means of thelateral hooks (5), and a rubber piece that will exert a force of 400–450gf is provided between the head-piece and the lateral hooks. The freeends of the lateral hooks (5) are adjustably positioned in the lateralopenings (7) of the chin-cup, according to the facial dimensions of thepatient, and fixed by means of the fixing member (9). The removable orfixed anchorage unit (13) is placed to the upper palate. The front hooks(2) are attached to the front openings (6) after being adjustedaccording to the facial structure of the patient and fixed by means ofthe fixing member (9).

The fastening members (8) are made of a flexible material such asrubber, and are placed between the front hooks (2) and the anchorageunit (13) within the mouth, on both sides, i.e., at left and right, insuch a manner that they will each exert a force of 350 gf.

The treatment is continued until an adequate vertical and horizontalclosure between the upper and lower incisors is obtained. When anadequate closing in the horizontal direction is obtained, the fronthooks (2) are removed but as the vertical growth and development takemore time, the lateral hooks (5) are used for a longer time. The devicecan be adapted to a smaller size by removing the unused hooks (2,5) fromthe chin-cup (1).

In another embodiment of the present invention, the lateral hooks arepermanently fixed on the chin-cup.

With this invention, in the skeletal and dental open-bite casesaccompanied by maxillary development deficiency in growing individuals,the maxillary forward development is obtained and the sagging of themandible downwards due to excessive growth of the mandible in thevertical direction is inhibited. The device according to the presentinvention is easy to manufacture and has a low cost of production.

1. A maxillary protraction device for correcting open-bite anomaliesaccompanied by maxillary deficiency, comprising: a chin-cup; one or morefront hooks on the front section of the chin-cup to exert a forcehorizontally and forwards to the maxilla; at least two lateral linearhooks located at the sides of the chin-cup to exert a vertical upwardforce to the mandible; means on the chin-cup defining front and lateralopenings each receiving therein one of the hooks, the one or more fronthooks and the lateral hooks each being lengthwise adjustable in itscorresponding opening; and fixing members releasably fixing respectiveones of the hooks in respective ones of the openings.
 2. A maxillaryprotraction device according to claim 1; wherein each front hook isremovable from its corresponding opening.
 3. A maxillary protractiondevice according to claim 1; wherein the lateral hooks are removablefrom their corresponding openings.
 4. A maxillary protraction deviceaccording to claim 1; wherein each front hook has a linear lower sectionslidably inserted into one of the openings and a curved upper sectionfor connection to an anchorage unit.
 5. A maxillary protraction deviceaccording to claim 1; further including elastic fastening members eachhaving one end connected to a head-piece and another end connected toone of the lateral hooks for exerting a vertical upward force on themandible.
 6. A maxillary protraction device according to claim 1;wherein the openings have a depth which is at least equal to the lengthof a linear section of the hooks.
 7. A maxillary protraction deviceaccording to claim 1; wherein the fixing members comprise screwsremovably screwed into screw holes that open into respective ones of theopenings for releasably fixing the hooks in the openings.
 8. A maxillaryprotraction device for correcting open-bite anomalies accompanied bymaxillary deficiency, comprising: a chin-cup configured to fit over thechin of a person using the device; one or more front fixtures disposedat a front portion of the chin-cup, each front fixture having an openingtherethrough that extends in a generally up-down direction during use ofthe device; two side fixtures disposed at opposite sides of thechin-cup, each side fixture having an opening therethrough that extendsin a generally front-rear direction during use of the device; a fronthook member adjustably slideably inserted in the opening of each frontfixture and releasably fixed in a desired up-down position in theopening by the front fixture; and a side hook member adjustablyslideably inserted in the opening of each side fixture and releasablyfixed in a desired front-rear position in the opening by the sidefixture.
 9. A maxillary protraction device according to claim 8; whereinthe front and side fixtures each have a hole therein extending from aperiphery thereof to the opening, and a locking member extending intothe hole and releasably engaging with the hook member to releasably fixthe hook member in the desired position.
 10. A maxillary protractiondevice according to claim 9; wherein the holes in the fixtures are screwholes and the locking members are screws screwed into the screw holes.11. A maxillary protraction device according to claim 8; furtherincluding elastic members each having one end connected to one of theside hook members and another end connected to a head-piece wearable bythe person using the device.
 12. A maxillary protraction deviceaccording to claim 8; further including an anchorage unit wearable inthe mouth of the person using the device and connected to each fronthook member.